Change bin/chunk-options.R to use .language-r instead of r

bin/chunk-options.R

@@ -37,7 +37,7 @@ opts_chunk$set(tidy = FALSE, results = "markup", comment = NA,
 hook_in <- function(x, options) {
   stringr::str_c("\n\n~~~\n",
                  paste0(x, collapse="\n"),
-                 "\n~~~\n{: .r}\n\n")
+                 "\n~~~\n{: .language-r}\n\n")
 }
 
 hook_out <- function(x, options) {